Property consultant Margot Berney confirmed the sale was settled last Friday.
Due to privacy issues, Mrs Berney was unable to identify who bought the courthouse but did say it was a "local".
The courthouse, on the corner of Paisley and Renfrew Sts, was added to Heritage New Zealand’s list of historic places in January this year.
Mrs Berney believed the new owners planned to develop the building for accommodation.
The building was designed by Invercargill architect John Mair and built in 1926.Development or alterations to the building are limited by its classification as a Category 2 historic building. However, some work is possible with the approval of Heritage New Zealand.
Four buildings were sold as part of the deal which included the original courthouse, an administration block, a storage building and a toilet block, Mrs Berney said.
The courthouse was closed in 2011 due to concerns over earthquake strengthening and court services were transferred from Balclutha to Dunedin.
